CloudFormation wrapper should recover from panics

[aidansteele]

aws-lambda-go/cfn/wrap.go

Line 14 in ec2fec7

type CustomResourceLambdaFunction func(context.Context, Event) (reason string, err error)

If a CustomResourceLambdaFunction (definition above) panics, it is recovered from in the generic Lambda handling below:

aws-lambda-go/lambda/function.go

Lines 26 to 34 in 02a038f

	if err := recover(); err != nil {
	panicInfo := getPanicInfo(err)
	response.Error = &messages.InvokeResponse_Error{
	Message: panicInfo.Message,
	Type: getErrorType(err),
	StackTrace: panicInfo.StackTrace,
	ShouldExit: true,
	}
	}

This will cause stack creations/updates to hang for a long time, as CloudFormation has a very long timeout waiting for a response. It would be a significant improvement if the custom resource wrapper recovered from panics and sent the error to the CloudFormation service.

Is this something you would be open to? I would be happy to submit a PR for review if you are ok with the idea.

[bmoffatt]

Sounds like a good idea to me!